system is assured by a unique diaphragm-type
economizer. This type of economizer, which may be
removed without disassembling the remainder of the
carburetor, insures accurate response to variations in
engine load conditions.
These new features have been incorporated in this
carburetor in conjunction with many of the time-proved
engineering refinements found in other Holley carburetor
models. The carburetor is fully sealed and balanced, with
all air bleeds and vents being open only to the air cleaner.
This filtered air supply gives added protection against the
accumulation of foreign matter in the carburetor passages.
The main jet and other fuel metering components are
individually flow tested to insure proper calibration of the
carburetor. Smoother acceleration is assured by the
prolonged discharge of fuel provided by the spring
overriding feature of the diaphragm type accelerating
pump. The fully-automatic vacuum-actuated power
enrichment system of improved design provides the
enriched mixture required for high power operation.
HOLLEY CARBURETOR MODEL 1904 FOR
AUTOMATIC TRANSMISSION ENGINE
2. APPLICATION
HOLLEY CARBURETOR MODEL 1904
WITH ALTITUDE ADJUSTMENT
NOTE
Carburetor part numbers and other information applicable
to specific I.H.C. vehicles may be obtained from the
current Holley Carburetor Parts Catalog Sheets for these
carburetors.
3. MAJOR SUBASSEMBLIES
This carburetor model is composed of two subassemblies:
the main body assembly and the throttle body assembly.
The die cast main body contains the float and fuel inlet
valve, the fuel bowl, the carburetor air inlet, the venturi,
the choke mechanism, the economizer diaphragm and stem
assembly, the accelerating pump, the main well and
economizer body assembly, the main nozzle, and the pump
discharge nozzle. Included in the main well and
economizer body assembly are a large part of the various
fuel metering components and fuel passages of the
.
carburetor. The cast iron throttle body contains the throttle
plate, the idle discharge ports, the distributor vacuum port,
and the idle speed and mixture adjusting screws.
This carburetor model is used on the International
Harvester Company 220 SD, 240 SD, 269 BD, 282
BD (C. O. E.), and 282 BD truck engines.
On the carburetor used with automatic transmission
engines, the dashpot assembly is mounted on a boss on the
side of the main body.
OPERATION
The fuel-air requirements of an automotive engine
vary considerably throughout its range of operation.
To assure effective carburetion, the
carburetor must supply an efficient but economical
mixture for normal cruising conditions, a richer
mixture when a high power output is desired,
